As described in, for example, JP2001-239892A (hereinafter referred to as Patent reference 1), a roof rail which is assembled on a roof upper surface of a vehicle is known. The known roof rail of Patent reference 1 includes a roof rail main body which is arranged to be extended in a vehicle front/rear direction and a cap which is assembled to a front end portion of the roof rail main body. Each of the roof rail main body and the cap is made from synthetic resin material. The cap is formed to have a hollow. An opening portion is provided at a rear end portion of the cap. The front end portion of the roof rail main body is inserted in the cap from the opening portion. Thus, the front end portion of the roof rail main body is covered with the cap. According to this configuration, a front end of the roof rail main body is expandable and contractible in the front/rear direction in the cap in a case where the roof rail main body is expanded and/or contracted in the vehicle front/rear direction due to changes in an ambient temperature. As a result, the front end of the roof rail main body and the opening portion of the cap are restricted from being away from each other in the vehicle front/rear direction in such a way that the front end of the roof rail main body comes to be positioned rearward relative to the opening portion of the cap. That is, it is restricted that a gap is formed between the roof rail main body and the cap.
According to the known roof rail of Patent reference 1, a step is formed at a boundary portion between the roof rail main body and the cap. Thus, an external appearance of the roof rail is impaired. In addition, an air flow, which is generated on or above the roof while the vehicle is running, impacts or collides with the step, and thus wind noise may be generated.
A need thus exists for a roof rail which is not susceptible to the drawback mentioned above.